The present invention relates to a device for transmitting information between at least two elements of an automobile vehicle and a method for transmitting information by use of said device.
More particularly, the invention relates to devices for a differential transmission of items of information which were developed in the course of the designing of transmission systems for an automobile vehicle owing to a number of problems concerning these applications and in particular disturbances liable to disturb these transmissions.
The use of the differential transmission provides a good immunity from these disturbances but it has a number of drawbacks as concerns its reliability.
Indeed, this reliability is related to the reliability of the connecting means (microswitching, oxidation of the contacts, etc. . .), the possibility of one of the transmission wires of contacting the body of the terminal of the battery, which prevents the correct operation of this type of transmission system.
An object of the invention is therefore to solve these problems by providing an information transmitting device which is reliable, simple, cheap and permits ensuring a sufficient transmission of information even when one of the transmission lines is subjected to a disturbance.
The invention therefore provides a device for the differential transmission of items of information between at least two elements of an automobile vehicle, each of which elements comprises information transmitting means and information receiving means connected by two information transmission lines, said device further comprising means for processing signals circulating in the information transmission lines whereby to permit an operation of the device in a degraded mode with signals circulating on one of the information transmitting line.
Advantageously, the processing means comprise means for establishing the derivative of the signals circulating in the information transmitting lines and means for shaping the output signals of said derivative establishing means, provided in the receiving means of each element.
According to another aspect, the invention also provides a method for transmitting items of information by employing a device such as that just defined in which one of the elements is a master element and the other a slave element, the master element delivering a synchronization word before each message, and the slave element transmitting a message in response, wherein the slave element also delivers a synchronization word before transmitting the response message thereof.